Pistons and piston packing for internal combustion engines



Feb. 19, 1957 J. L. HARRAH 2,782,082

PISTONS AND PISTON PACKING FOR INTERNAL COMBUSTION ENGINES Filed Oct. 12, 1955 United States. Patent '0 ice PISTONS AND PISTON PACKING FOR INTERNAL COMBUSTION ENGINES John L. Harrah, Bedford, Ohio Application October 12, 1953, Serial No. 385,535

Claims. (Cl. 30914) This invention relates generally to improvement in pistons and piston packing for use in internal combustion engines.

The primary object of the invention is to provide an improved form of piston and packing construction whereby the packing may be removed and replaced from the top of the motor without disturbing the precision finished parts of the engine.

Another object of the present invention is to provide a piston and packing to prevent loss of compression pres.- sure due to leakage between the pistons and the cylinder walls, and also to retain the motor oil in the crank case.

Another object of the invention is to provide a detachable one piece packing having a helically extending rib thereon forming a sealing relation against the cylinder walls and to provide a piston construction being so proportioned so as to receive the improved form of packing.

These and other objects as well as the nature and advantages of the invention will be more readily apparent from the following description taken in connection with the accompanying drawings andin which:

Fig. 1 is an elevation side view of a piston.

Fig. 2 is a plan view of one section of the cap ring.

Fig. 3 is a side view of the cap ring.

Fig. 4 is a sectional view of the cap ring..

Fig. 5 is a plan view of the second section of the cap ring.

Fig. 6 is a side view of the same ring.

Fig. 7 is a plan view of the packing.

Fig. 8 is an elevational side view of the packing.

Referring more particularly to the drawings and in Fig. 1 it can be seen that the piston, generally indicated by numeral .15, comprises a main body 16, and an inner and outer ring 17 and 18, which will for the sake of brevity be hereinafter referred to as the cap ring 19.

The main body 16 consists of a substantially thick, hollow, cylindrical portion, having a skirt 20, a reduced portion 23, and with wrist pin bosses 21 and 22 positioned immediately above said skirt 20. Said main body 16 being open at one axial end and closed at the opposite axial end. The outer periphery of the closed end 26 is stepped inwardly, thereby, forming a shoulder 27 and 2,782,082 Patented Feb. 19, 1957 slightly tapered, as indicated by numeral 31. The outer surface of said inner ring 17 is disposed with threads 32. I

The inside surface of the outer ring 18 is disposed with a thread 33 and being so proportioned to be screwed downwardly around the threads 32 of the inner ring 17.

By screwing the outer ring 18 down around the inner ring 17 the two sections 28 and 29 are each pressed firmly against the wall of the piston, the tapers 24 and 31 are in direct alignment and the lugs 30 are securely received in the apertures 25.

The piston packing 34 is of substantially thick, annular construction and being disposed with a slot 35 extending therethrough. The slot 35 being cut diagonally to the axis of the packing, thereby preventing leakage through the slot 35.

Said packing 34 comprising a back member 36 with its outer periphery being disposed with a helically extending rib 37. Said packing 34 being so proportioned so as to be slipped over the neck 14 of the piston and resting being somewhat smaller in diameter than the skirt section 20. This reduced portion 23 is for the purpose of carrying an improved form of piston packing.

The upper edge of said reduced portion 23 is stepped slightly inwardly providing a tapered surface 24. The periphery of said reduced portion 23 is possessed with a plurality of inwardly extending apertures 25, located immediately below the tapered surface 24.

The detachable cap ring 19 comprising two annular, inner and outer rings 17 and 18 are of substantially thick, annular construction. The inner ring 17 consists of two separate sections 28 and 29, and each of these sections are disposed with a plurality of inwardly extending lugs 30. The annular space directly above said lugs 30 is on the shoulder 27 of the piston body 16.

An annular back-up spring (indicated with numeral 38 in Fig. 1), is placed between the packing 34 and the piston wall to force the helically extending rib 37 against the cylinder walls.

Thus constructed: The packing 34 is lowered down around the neck 14 of the piston and an annular back-up spring 38 is placed between said packing 34 and the wall of said piston neck 14. The two sections 28 "and 29 comprising the inner ring 17 are placed around the piston neck 14, immediately above said packing 34, with the lugs 30 being received in the provided apertures 25. The two sections are abutted end to end, thereby forming an annular threaded surface.

The outer ring 18 is then screwed downwardly around the inner ring 17 and securely tightened.

The two piece cap ring 19 is heat treated before using and one of its purposes is to allow its being usedon aluminum alloy, cast iron, steel, or any other suitable piston material.

The threaded portions of the inner and outer cap ring are tapered to insure a tight fit when it is received upon the reduced portion.

The applicant has learned that threads integrally arranged with the piston body are not entirely satisfactory because of the piston expansion and the effects of the heat upon the threaded parts.

The pistons constructed with the removable cap ring 19 would allow the piston packing to be removed and replaced from the top of the motor. The helical rib 37 would control the compression pressure and the blow by of internal combustion engines and retain the motor oil in the crank case.

For these and other reasons it is to be understood that the illustrative construction shown may be modified in various respects without departing from the spirit and scope of my invention and it will be understood that it is my intention to include all such modifications in the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In combination, a cylindrical piston comprising a main body having a crown and skirt portion; said main body having wrist pin bosses positioned immediately above said skirt; a sectional cap ring consisting of an inner and an outer ring, each of said rings having coacting threaded surfaces extending thereon; a piston packing comprising an annular back member whose outer periphery is disposed with a transverse helically extending rib thereon, said packing having a slot extending therethrough; the upper periphery of said piston being so proportioned so as to properly receive said packing; said cap ring being positioned immediately above said packing being engaged with the upper peripherical edge of said main body, said cap ring retaining said packing around said piston.

2. In combination, a cylindrical piston comprising a main body having a skirt with wrist pin bosses positioned immediately above said skirt, said piston being open at one axial end and closed at the opposite end; a piston packing comprising an annular back member whose outer periphery is disposed with a transverse helical rib thereon, said packing having an axially extending slot therethrough; a sectional cap ring having an inner and outer section, each of said sections having coacting threaded surfaces thereon; said packing being so porportioned to be received around the upperperiphery of said piston body and being retained thereon with said cap ring being securely assembled around, the upper circumferential edge of said piston body. a

3. In combination, a cylindrical piston having askirt with wristpin bosses positioned immediately above said skirt; said piston being open at one axial end and closed at the opposite end, said piston having a plurality of inwardly extending apertures positionednear the upper out side surface of said piston; a piston packing of substantially thick annular construction comprising a back memher with its outer periphery being disposed with a helical rib extending thereon, said packing being axially cut therethrough and being so proportioned to be received around said piston body; a cap ring consisting of an inner and an outer ring, said inner ring having a plurality of lugs extending inwardly therefrom, each of said rings having a correlative threaded surface and being formed to be received around the upper periphery of said piston; said lugs of said cap ring to communicate with said apartures in said, piston body and being in alignment thereon, said cap ring to retain said packing securely upon said piston body.

4. In combination, a piston of substantially thick, cylindrical construction, comprising a main body having a crown and a skirt portion; Wrist pin posses positioned immediately above said skirt; a detachable cap ring consisting of an inner and an outer ring; each of said rings having a correlative threaded surface, said outer ring being -so proportioned to be received around said inner ring; a

piston packing comprising an annular back member whose outer periphery is disposed with a helical rib extending thereon, said packing having a slot extending therethrough; said packing being so proportioned to be received upon said piston body positioned immediately above said wrist pin bosses; said cap ring being so proportioned to be received upon said piston body positioned immediately above said packing; said detachable cap ring to securely hold said packing upon said piston body.

5. In combination, a piston of substantially thick, cylindrical construction, having a crown and a skirt portion, with wrist pin bosses positioned immediately above said skirt; the upper periphery of said piston having circumferentially extending space provided for the purpose of carrying an improved form of piston packing; a piston packing of substantially thick, annular construction being v in the form of a circle, said packing comprising a back member with its outer periphery being disposed with circumferentially extending ribs with a series of grooves extending between said ribs, said packing having a slot extending from one side through to the opposite side and being so proportioned to be received around the space provided in the upper periphery of said piston; a back up spring being provided to force the ribs of said packing toabear against the cylinder walls; a cap ring being in the form of a circle and consisting of two substantially thick separate portions, an inner and an outer portion, said cap ring portions to be securely engaged near the upper circumferential edge of said piston to securely retain said packing around said piston.

References Cited in the file of this patent UNITED STATES PATENTS 1,538,874 Short May 19, 1925 1,747,568 Blomgren Feb. 18, 1930 ;2.043,424 Campbell June 9, 1936 2,294,519 Starr Sept. 1, 1942 FOREIGN PATENTS 107,868 Australia June 22, 1938 123,439 Australia Nov. 3, 1944 

